1. Field of the Invention
The present invention relates to method and apparatus for message communication, and particularly to method and apparatus for message communication with an improved operability for message communication by adding information indicative of message communication to call setting information transmitted from a calling terminal connected to an integrated services digital network when a call is originated, and by switching the called terminal to a message mode according to this information.
2. Description of the Related Art
Recently, apparatuses capable of performing message communication in addition to usual voice communication with PHS (personal handyphone system), etc., have been proposed in Japan.
The message communication is a communication in which predetermined message data or message data input through a keypad is transmitted from a calling terminal to a called terminal, and the transmitted message data is displayed on a display in the called terminal.
The procedure of a conventional message transmission in a PHS, etc., capable of performing the message communication is as follows.
1) Select predetermined message data or prepare message data through operation of a keypad on the calling terminal. PA1 2) Input the telephone number of the called terminal to effect call operation. PA1 3) When the called terminal responds, tell the called terminal that the call is a message communication and ask the called terminal to switch the operation to the message reception mode. PA1 4) Transmit the message data selected or prepared in 1).
As seen in the foregoing, the conventional message transmission procedure in a PHS, etc. requires the called terminal to manually switch its operation to the message reception mode after the called terminal responds to the incoming signal from the calling terminal. Therefore, the operations of effecting message communication are troublesome, and the problem is that message communication cannot be effected in such an event that nobody is present or no response is made at the called terminal because in such an event the called terminal cannot be switched to the message reception mode.
In order to resolve the problems, a system could be considered in which the called terminal automatically responds to the incoming signal from the calling terminal and switches its operation to the message reception mode. However, in such a system, the called terminal automatically responds to not only incoming signals for message communication but also incoming signals other than that for message communication, for example incoming signals for usual voice communication, so as to switch its operation to the message mode. This results in that the call is considered to be responded with a non-signal response and the caller has to pay this unnecessary calling charge.